Tariquidar (XR9576): a P-glycoprotein drug efflux pump inhibitor

Expert Rev Anticancer Ther. 2007 Apr;7(4):447-59. doi: 10.1586/14737140.7.4.447.


P-glycoprotein actively transports structurally unrelated compounds out of cells, conferring the multidrug resistance phenotype in cancer. Tariquidar is a potent, specific, noncompetitive inhibitor of P-glycoprotein. Tariquidar inhibits the ATPase activity of P-glycoprotein, suggesting that the modulating effect is derived from the inhibition of substrate binding, inhibition of ATP hydrolysis or both. In clinical trials, tariquidar is tolerable and does not have significant pharmacokinetic interaction with chemotherapy. In patients, inhibition of P-glycoprotein has been demonstrated for 48 h after a single dose of tariquidar. Studies to assess a possible increase in toxicity of chemotherapy and the impact of P-glycoprotein inhibition on tumor response and patient outcome are ongoing. Tariquidar can be considered an ideal agent for testing the role of P-glycoprotein inhibition in cancer.

Publication types

  • Review

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / antagonists & inhibitors*
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Animals
  • Antineoplastic Agents / therapeutic use*
  • Drug Resistance, Multiple*
  • Drug Resistance, Neoplasm*
  • Humans
  • Neoplasms / drug therapy
  • Neoplasms / epidemiology
  • Neoplasms / metabolism
  • Protein Transport / drug effects
  • Protein Transport / physiology
  • Quinolines / administration & dosage
  • Quinolines / pharmacology*


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Antineoplastic Agents
  • Quinolines
  • tariquidar